Privacy Mode Comparison

All of the browsers today provide a privacy browsing mode.  This mode is generally aimed at reducing or eliminating the storage of data locally on the user’s computer and limiting the information given to remote parties.  In some cases, this mode also affects data – specifically, cookies – transmitted by the browser. The privacy mode feature achieves results similar to the “clear private data” menu option.

Privacy Mode Chrome 7: Incognito Firefox 3.6 / 4.0 beta 6: Private Browsing Internet Explorer 8 / 9 Beta: InPrivate Browsing Opera 10.6: Private Tab/Window Browsing Safari 5: Private Browsing
Does not keep visited sites in the browser history Yes Yes Yes Yes Yes
Does not keep downloaded files in the download history1 Yes Yes Limited2 Yes Yes
Does not save form fields data (including passwords) Yes Yes Yes Yes Yes
Does not save addresses typed into the address bar Yes Yes Yes Yes Yes
Does not remember visited links Yes Yes Yes Yes Yes
Does not save search queries Yes Yes Yes Yes Yes
Deletes cached files at the end of the browsing session Yes Yes Yes Yes Yes
Does not read existing third-party cookies Yes Yes Yes Yes Yes
Deletes new cookies at the end of the session Yes Yes Yes Yes Yes
Blocks referring URL from being sent No No No No No
Disables browser plug-ins3 No4 No No No No
Disables browser extensions5 Yes No Yes NA No
Disables automatic online address bar search service (if browser supports) Yes NA Yes6 NA NA
Disables online site suggestion service (if browser supports) NA NA Yes NA NA
Operates on a per-window basis Yes No Yes Yes No
Persists when user exits and re-starts the browser No No No No No
Can be set to automatically start when browser is launched No Yes No No No

1 Although the browser may not directly store the download history, the files remain on the operating system until deleted.

2 If a user opens the file, IE stores that information in the History under “Computer” and this history is not removed when the user leaves the InPrivate Browsing mode.

3 A browser plug-in is a third party application that interacts with the browser, but does not run natively in the browser.  An example of a plug-in is Adobe Flash Player.

4 Chrome Incognito runs plug-ins in an off-the-record mode that sets a flag indicating user data should not be stored.  However it is up to the plug-in to honor the flag.

5 A browser extension (or add-on) runs natively in the browser.  An example of an extension is AdBlock Plus for Firefox.

6 Internet Explorer 9 Beta has an integrated search service in the address bar that users may choose to opt into when browsing in normal mode. In InPrivate Browsing this service is disabled by default. Users can re-enable it in the address bar during InPrivate Browsing if they choose to do so.

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